It's OK, just fine, for vinyl in the south. However, the THINNER vinyl may warp due to the high heat, especially in the S-West. (The homes there are usually stucco, concrete, brick, adobe, etc., etc..) In the NE where temps fluxuate a lot, the thinner vinyls can warp and crack too. That's why it's best to go with a .042 or better vinyl.
The lighter the color, too, the less heat is absorbed. That adds to the wharping problem too.